Method and apparatus for fluid flow control

ABSTRACT

The invention provides a method and apparatus to control fluids such as process gases into two or more substrate process chambers. In one aspect, the gas flow from a first supply to a first processing region is used to control the gas flow of a second supply to a second processing region where the total gas flow is about equal to the total of the gas flows into both the first and second processing regions. In another aspect, the gas flow rate from the first supply for the first processing region is about equal to the gas flow rate for the second supply to the second processing region.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method and apparatus for fluid flow control.More specifically, the invention relates to splitting a fluid flow suchas a gas flow into pre-selected proportions.

2. Background of the Related Art

A chip manufacturing facility is composed of a broad spectrum oftechnologies. Cassettes containing semiconductor substrates are routedto various stations in the facility where they are either processed orinspected. Semiconductor processing generally involves the deposition ofmaterial onto and removal (“etching”) of material from substrates.Typical processes include chemical vapor deposition (CVD), physicalvapor deposition (PVD), electroplating, chemical mechanicalplanarization (CMP), etching and others.

Conventional substrate processing systems often process substratesserially, ie., one substrate at a time. Unfortunately, processingsubstrates serially results in throughput limitations corresponding toan individual substrate process time. To overcome the limitations ofserial processing, batch (i.e., parallel) processing is often employed.Batch processing allows several substrates to be processedsimultaneously using common fluids such as process gasses, chambers,processes, etc. thereby decreasing equipment costs, and increasingthroughput. Ideally, batch-processing systems expose each of thesubstrates to an identical process environment whereby each substratereceives the same process gases and plasma densities for uniformprocessing of the batch.

One method for batch processing is performed in large single chamberbatch-processing systems designed to accommodate more than onesubstrate. Unfortunately, as the substrates within a singlebatch-processing chamber share a common area, process gasses and plasmadedicated to one substrate will often intermix with the process gasesand plasma dedicated to another substrate causing process variationswithin each substrate batch. To minimize the intermixing issue, internalchamber divider walls may be used that form sub-chambers within thesingle batch-processing chamber. However, chamber divider walls increasethe cost and complexity of the batch-processing chamber. To eliminatethe need for divider walls, multiple single-substrate processingchambers in tandem are often used to provide the benefits of batchprocessing and uniformity while allowing the careful control andisolation of the process environment for each substrate within a batch.

To control the individual process for each substrate within abatch-processing environment, individual gas, power, and plasma systemsare often incorporated within the processing chambers or sub-chambers.In addition, there is usually an individual gas delivery system for eachgas or mixture of gases. To reduce the cost of multiple gas supplies andprocess controls each individual processing region generally has commongas connections and sources. For example, the gas supplies for eachsub-chamber or single-substrate processing chamber generally are coupledto a common gas source eliminating the need for multiple gas sources forthe same gas or mixture of process gases. Unfortunately, due tovariations in gas flow within each individual gas delivery system, eachgas delivery system must be individually monitored and calibrated sothat each substrate receives the same amount of process gas flow foreach process step, according to the process regime. The variations ingas flow rates for each chamber are due to the flow resistance thatdepends upon the size of pipe used, length of pipe, and pipe joints,valves, etc. of the gas delivery systems.

To alleviate the calibration and control of each individual gas systemfor the single chamber or multi-chamber types of batch-processingsystems, a centralized gas control system is often used to monitor andcontrol the gas flow. Unfortunately, centralized gas control systemsgenerally increase the complexity and cost of the processing systems.Thus, regardless of the batch processing system used, conventionalindividual gas delivery systems are often complex, require individual orcentralized monitoring, require individual calibration, and generallyincrease the cost of production.

Therefore, there is a need for method and apparatus to provide a uniformfluid flow to each chamber within a batch-processing system in a simpleand cost effective manner.

SUMMARY OF THE INVENTION

Aspects of the invention generally provide a fluid delivery system forcontrolling and dividing fluids such as process gases used in substrateprocessing. In one embodiment, the invention provides an apparatus fordividing a gas flow from a gas source, including a first gas lineconnected to a gas source, a gas flow meter positioned on the first gasline to output a signal corresponding to a gas flow rate through thefirst gas line, a second gas line connected to the gas source, and a gasflow controller positioned on the second gas line and responsive to thesignal from the gas flow meter to divide the gas flow from the gassource.

In another embodiment, the invention provides an apparatus for dividinga gas flow from a gas source output into a tandem-processing chamber,including a first gas line connecting a gas source output to a firstprocessing region of a tandem processing chamber, a gas flow meterpositioned on the first gas line to output a signal corresponding to afirst gas flow rate through the first gas line, a second gas lineconnecting the gas source output to a second processing region of thetandem processing chamber, and a gas flow controller positioned on thesecond gas line and responsive to the signal from the gas flow meter todivide the gas from the gas source output between the first gas flowrate through the first gas line to the first processing region and asecond gas flow rate through the second gas line to the secondprocessing region.

In still another embodiment, the invention provides a method of dividinga fluid flow from a fluid source, including measuring a first fluid flowrate through a first fluid line connected to the fluid source, andcontrolling a second fluid flow rate through a second fluid lineconnected to the fluid source using the first fluid flow rate throughthe first fluid line.

In another embodiment, the invention provides a method of dividing a gasflow in a tandem processing chamber including measuring a first gas flowrate from a gas source through a first gas line coupled to a firstprocessing region of a tandem processing chamber, and using the firstgas flow rate, controlling a second gas flow rate from the gas sourcethrough a second gas line coupled to a second processing region of thetandem processing chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features, advantages andobjects of the invention are attained and can be understood in detail, amore particular description of the invention, briefly summarized above,may be had by reference to the embodiments thereof which are illustratedin the appended drawings.

It is to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a plan-view of a prior art semiconductor batch-processing toolthat may be used to advantage.

FIG. 2A is a top perspective view of a semiconductor batch-processingtool of FIG. 1 including a gas delivery system of the invention that maybe used to advantage.

FIG. 2B is a bottom perspective view of the semiconductorbatch-processing tool of FIG. 1 including a gas delivery system of theinvention that may be used to advantage.

FIG. 3 is a cutaway view of the tandem-processing chamber of FIG. 1including the gas delivery system of FIGS. 2A and 2B.

FIG. 4 is a diagrammatic view illustrating the gas flow control loop ofthe invention that may be used to advantage.

FIG. 5 is a diagrammatic view illustrating two gas flow control loops ofthe invention that may be used to advantage.

FIG. 6 is a diagrammatic view of one embodiment of a gas flow measuringapparatus illustrating a flow constriction of the invention that may beused to advantage.

FIG. 7 is a flow diagram of the invention illustrating a method of gasflow control that may be used to advantage.

FIG. 8 is a graphical illustration of the results of an exampletandem-chamber substrate deposition process without gas flow control.

FIG. 9 is a graphical illustration of the results of an exampletandem-chamber substrate deposition process of the invention that may beused to advantage.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Aspects of the invention generally provide a fluid delivery system forcontrolling and dividing fluids such as process gases used in substrateprocessing. In accordance with one aspect of the invention, the systemis a staged vacuum system which generally includes a load lock chamberfor introducing substrates into the system, a transfer chamber forhousing a substrate handler, and one or more processing chambers eachhaving two or more processing regions which are isolatable from eachother and preferably share a common fluid supply and a common exhaustpump. Isolatable means that the processing regions have a confinedplasma zone separate from the adjacent region that is selectivelycommunicable with the adjacent region via an exhaust system. Theprocessing regions within each chamber also preferably include separatefluid distribution assemblies and RF power sources to provide a uniformplasma density over a substrate surface in each processing region. Theprocessing chambers are configured to allow multiple, isolated processesto be performed concurrently in at least two regions so that at leasttwo substrates can be processed simultaneously in separate processingregions with a high degree of process control provided by shared gassources, shared exhaust systems, separate gas distribution assemblies,separate RF power sources, and separate temperature control systems. Forease of description, the terms processing region and chamber may be usedto designate the zone in which plasma processing is carried out.

FIG. 1 is a plan view of one embodiment of a tandem semiconductorprocessing system 100 in which embodiments of the invention may be usedto advantage. The arrangement and combination of chambers may be alteredfor purposes of performing specific fabrication process steps.

The tandem-chamber processing system 100 is a self-contained systemhaving the necessary processing utilities supported on a mainframestructure 101 which can be easily installed and which provides a quickstart up for operation. The substrate processing system 100 generallyincludes four different regions, namely, a front end staging area 102where substrate cassettes 109 are supported and substrates are loadedinto and unloaded from a loadlock chamber 112, a transfer chamber 111housing a substrate handler 113, a series of tandem-process chambers 106mounted on the transfer chamber 111 and a back end 138 which houses thesupport utilities needed for operation of the system 100, such as a gaspanel 103, and the power distribution panel 105 for RF power generators107. The system can be adapted to accommodate various processes andsupporting chamber hardware such as CVD, PVD, etch, and the like.

FIGS. 2A and 2B illustrate a perspective top view and bottom viewrespectively of one embodiment of a tandem-processing chamber 106 thatincludes the gas delivery system of the invention. The tandem-processingchamber 106 includes a chamber body 102 mounted or otherwise connectedto the transfer chamber 111 and includes two cylindrical annularprocessing regions in which individual substrates are concurrentlyprocessed. The chamber body 102 supports a lid 104 that is hindgedlyattached to the chamber body 102 and includes one or more gasdistribution systems 108 for delivering reactant and cleaning fluidssuch as process gases and gas mixtures into the processing regionstherein.

FIG. 3 shows a cross-sectional view of the tandem-processing chamber 106for use with aspects of the invention. The tandem-processing chamber 106includes a chamber body 102 having a sidewall 112, an interior wall 114,and a bottom wall 116. The sidewall 112 and the interior wall 114 definethe two cylindrical annular processing regions 118, 120. The bottom wall116 of the processing regions 118, 120 defines at least two passages124, 122 through which a stem 126 of a pedestal heater 128 and a rod 130of a substrate lift pin assembly are disposed, respectively. Acircumferential pumping channel 125 is formed in the interior chamberwalls 114 for exhausting gases and controlling the pressure within eachregion 118, 120. A chamber liner or insert 127, preferably made ofceramic, glass, quartz, or the like, is disposed in each processingregion 118, 120 to define the lateral boundary of each processing region118, 120 and to protect the chamber walls 112, 114 from the corrosiveprocessing environment, and to maintain an electrically isolated plasmaenvironment. The liner 127 is supported in the chamber on a ledge 129formed in the walls 112, 114 of each processing region 118, 120. Theliner includes a plurality of exhaust ports 131, or circumferentialslots, disposed therethrough and in communication with the pumpingchannel 125 formed in the chamber walls where the pumping channel 125 isconnected to a common vacuum source (not shown). Preferably, there areabout forty-eight ports 131 disposed through each liner 127 which arespaced apart by about 7.5° and located about the periphery of theprocessing regions 118, 120. While forty-eight ports are preferred, anynumber can be employed to achieve the desired pumping rate anduniformity. In addition to the number of ports 131, the height of theports 131 relative to the gas distribution system 108 is adapted toprovide an optimal gas flow pattern over the substrate duringprocessing. In addition, the chamber body 102 defines a plurality ofvertical gas passages for each reactant gas and cleaning gas suitablefor the selected process. The gasses are delivered through the verticalpassages in the chamber body 102 into a gas distribution system 108disposed through the chamber lid 104 to deliver gases into theprocessing regions 118, 120, from a gas source such as the gas panel103.

The gas distribution system 108 of each processing region includes a gasinlet passage 140 that delivers process gases into a showerhead assembly142 from a gas inlet manifold 117. The showerhead assembly 142 iscomprised of an annular base plate 148 having a blocker plate 144disposed intermediate a faceplate 146. A plurality of o-rings 147 areprovided on the upper surface of the chamber walls 112, 114 around eachgas passage to provide sealing connection with the lid 104. The lid 104includes matching passages to deliver the gas from the vertical passageswithin the lower portion of the chamber 102 into the gas distributionsystem 108. Gas inlet connections 153 are disposed at the bottom 116 oftandem-processing chamber 106 to connect the gas passages formed in thechamber 102 to a first and a second gas delivery line 139, 141. In oneaspect, the base plate 148 defines a gas passage therethrough to deliverprocess gases to a region just above the blocker plate 144. The blockerplate 144 disperses the process gases over its upper surface anddelivers the gases above the faceplate 146. In one aspect, holes in theblocker plate 144 can be sized and positioned to enhance mixing of theprocess gases and distribution over the faceplate 146. The gasesdelivered to the faceplate 146 are then delivered into the processingregions 118, 120 in a uniform manner over a substrate positioned forprocessing.

In one aspect, an RF feedthrough (not shown) provides an electricalconduit through the walls 112, 114 to provide a bias potential to eachshowerhead assembly 142, facilitating the delivery of RF power for thegeneration of plasma between the faceplate 146 of the showerheadassembly and the heater pedestal 128. A cooling channel 152 is formed ina base plate 148 of each gas distribution system 108 to cool the baseplate 148 during operation. A fluid inlet 155 delivers a coolant fluid,such as water or the like, into the channels 152 that are connected toeach other by coolant line 157. The cooling fluid exits the channelthrough a coolant outlet 159. Alternatively, the cooling fluid iscirculated through the manifold 117.

FIG. 4 is a diagrammatic view illustrating a gas flow control loop forthe tandem-processing chamber 106 of FIGS. 1-3. As necessary, FIGS. 1-3are referenced in the following discussion of FIG. 4.

Illustratively, one or more fluids such as process gases, or a mixtureof process gasses, are supplied to the tandem-process chamber 106 fromthe gas panel 103 having a gas flow delivery system (GFD) 180 coupled tothe gas delivery lines 139,141. In one aspect, the GFD 180 includes asplitter 133 such as a line splitter, t-type, and the like having a gasinput coupled to a gas source line 132 from the gas panel 103. Thesplitter 133 includes a first splitter output 156 connected to a gasinput 183 of a gas flow measuring apparatus (GFM) 182, such as a gasflow meter, mass flow meter (MFM), and the like, and a second splitteroutput 158. The GFM 182 includes a flow output 185 and one or more flowmeasurement signal outputs 155 adapted to provide flow measurementsignals such as digital signals, analog signals, and the like,indicative of the amount of flow through gas delivery line 139. Further,the GFD 180 includes a gas flow control apparatus (GFC) 184, such as anadjustable gas flow controller, orifice, venturi, or a valve, such as agate valve, a ball valve, a pneumatic valve, and the like. The GFC 184also comprises a gas control input 190 coupled to the second splitteroutput 158, a gas control output 191 coupled to the second gas deliveryline 141, and a flow control input 161 coupled to and responsive to theflow measurement signal output 155 from the GFM 182. In one aspect, thesignal level of the flow measurement signal output 155 of the GFM 182 isa function of the gas flow through gas line 139 measured by the GFM 182.For example, as the gas flow increases through the GFM 182, the flowmeasurement signal from the signal output 155 may increase in voltage orcurrent. The gain of the flow control input 161 may be set such that aminimum voltage from the signal output 155 corresponds to a minimum flowand a maximum flow measurement signal output 155 corresponds to amaximum flow through the GFC 184. In another aspect, the gain of theflow control input 161 and flow measurement signal 155 have about thesame flow range so the control signal output 155 indicates that thetotal flow from the gas line 131 is divided into about a fifty percentflow through the GFM 182 and through the GFC 184 in a steady statecondition. Although it is preferred that the values of the minimum flowmeasurement signal 155 voltage is about zero volts and the maximumvoltage is about 5 volts, it is contemplated that the flow measurementsignal output 155 may be any value and type of signal such as voltage,current, power, electro-optical, or electromechanical, and the like.Further, it is contemplated that the flow measurement signal 155 may bea digital signal whereby the digital information controls the flowcontrol input 161. For example, the digital signal may be in a byteformat whereby the change in the byte value changes the flow through theGFC 184. In another aspect, a filter 177, such as a sintered nickelfilter available from PALL or Millipore, is disposed in the gas line 132upstream and/or downstream from the splitter 133. In still anotheraspect, the gas line 132 may be coupled to a mass flow controller withinthe gas panel 103 to establish a consistent input gas flow to the GFD180.

FIG. 4 is merely one hardware configuration for a GFD 180. Aspects ofthe invention can apply to any comparable hardware configuration,regardless of whether the GFD 180 is a complicated, multi-gas deliveryapparatus or a single gas delivery apparatus. For example, FIG. 5illustrates combining two GFDs to provide two or more different fluidsor mixtures of fluids to the tandem-processing chamber 106 where, forexample, a fluid such as a process gas A is delivered by a first GFD1180 and a second fluid such as a process gas B is delivered by a secondGFD 181.

FIG. 6 illustrates a diagrammatic view of one embodiment of a GFM 182.As necessary, FIGS. 1-5 are referenced in the following discussion ofFIG. 6.

In one aspect, the GFM 182 includes a gas flow restriction 187 such asan orifice, block, valve, and the like, adapted to provide gas flowresistance. The restriction 187 is sized to set the desired flow ratethrough the gas delivery line 139 to establish a desired initial gasflow rate through both gas lines 139, 141 and provide a gas flowresistance through gas delivery line 139. The split gas lines 139, 141share a common gas input 131 and are in communication through splitter133 whereby the flow through each line equals about the total gas flow.Therefore, a flow restriction within either gas delivery line 139, 141affects the gas flow through the other line. For example, if the gasflow were completely restricted through gas delivery line 139 and thegas delivery line 141 was unrestricted, then the gas would flow throughgas delivery line 141. In one aspect, the gas flow restriction 187includes an orifice 188 having an inner diameter of about 0.03 inches toabout 0.06 inches to provide the gas flow resistance. Thus, as a processgas flows through the GFM 182, the gas flow from gas delivery line 139is impeded by the gas flow restriction 187 creating backpressure withingas delivery line 139 causing process gas to flow through gas deliveryline 141. In one aspect, the gas restriction 187 may be a fixed value ormay be adjustable to further accommodate different process gases andflow requirements. In another aspect, the restriction 187 is a separatedevice coupled to any portion of gas line 139.

Fluid Flow Control

FIG. 7 is a flow diagram of one embodiment for a method 700 for fluidflow control for the tandem-processing chamber of FIG. 1 in accordancewith aspects of the invention. As necessary, FIGS. 1-6 are referenced inthe following discussion of FIG. 7.

FIG. 7 is entered at step 705 when, for example, a fluid such as aprocess gas is delivered from the gas line 131 to the GFD 180. At step710, the GFC 184 is set to minimum flow and the GFM 182 is set tomaximum flow. The process gas flows from the input gas line 131 to thesplitter 133 and then to each gas delivery line 139, 141. Initially, dueto the setting of the GFC 184 and GFM 182, the majority of the processgas flow occurs through the GFM 182. The flow through the GFM 182 ismeasured at step 715 and the corresponding flow measurement signal 155is then transmitted to the flow control input 161. The flow measurementsignal 155 then opens the flow of gas through the GFC 184. As the flowof process gas begins to flow through the GFC 184, the gas flow throughthe GFM is proportionally decreased. In one aspect, at step 725, thevalue of the flow measurement signal 155 corresponds to the input rangeof the flow control input 161 such that about fifty percent of theprocess gas flows through the GFM 182 and GFC 184. In one aspect, as thegas flows within the gas delivery lines 139, 141 are responsive to thegas flows of each other, and the GFM 182 controls the gas flow throughthe GFC 184 in accordance to the measured gas flow through the GFM 182,the individual flow through each gas delivery line 139, 142 is adjusteduntil the two flow rates are about equal and in equilibrium. Although, afifty percent flow through each gas delivery line 139, 141 is preferred,other ratios of gas flows are contemplated to allow for variationsbetween processing regions. If the gas flow rate is about identicalthrough GFM 182 and GFC 184, the gas flow is continued until the processstep is finished at step 730. Subsequently, the method 700 exits at step735. Thus, the gas lines 139, 141, and the flow control signal define aclosed loop gas control system responsive to the gas flow from the gasinput 131 where a change in gas flow results in a proportional change inthe gas flow rates through the gas lines 139, 141.

Example Process Parameters

In the described embodiment, the precursor gas may be any gas or gasmixture such as Trimethylsilane (TMS), NF₃, and the like, adapted toperform substrate processing operations. In one aspect, the flow rate ofactivated species is about 100 sccm to about 20 slm per minute and thechamber pressure is about 0.5 Torr to about 10.0 Torr. Within thedeposition chamber, the RF sources supply about 200 watts to about 2000watts to the plasma.

Though a RF generator is used in the described embodiment to activatethe precursor gas, any power source that is capable of activating theprecursor gas can be used. For example, the plasma can employcombinations of DC, radio frequency (RF), and microwave (MW) baseddischarge techniques. In addition, if an RF power source is used, it canbe either capacitively or inductively coupled to the inside of thechamber. The activation can also be performed by a thermally based, gasbreakdown technique, a high intensity light source, or an x-ray source,to name just a few.

In general, the reactive gases may be selected from a wide range ofoptions. For example, the reactive gas may be chlorine, fluorine orcompounds thereof that include carbon, oxygen, helium, or hydrogen, e.g.CF₄, SF₆, CF₆, CCl₄, CCl₆, SIO₂, etc. Of course, the particular gas thatis used depends on the material that is being deposited.

FIGS. 8 and 9 illustrate one example of a tandem process performed withand without using the fluid flow control apparatus and method describedabove. The following table presents one example of chamber operatingconditions for a deposition process performed in one embodiment of atandem-chamber of the invention for both FIGS. 8 and 9. With referenceto FIG. 8, the gas flow apparatus and method are not used. The leftchamber and right chamber show a difference in substrate thickness ofabout 5%. With reference to FIG. 9, the gas flow apparatus and methodare used. There is a less than about 1% difference in the substratethickness variation between the left and right processing regions.

Processing Parameter Parameter Value GAS: TMS About 500 sccm to about2000 sccm GAS: O₂ About 400 sccm to about 2000 sccm Chamber PressureAbout 0.5 Torr to about 10 Torr RF Power About 400 W to about 2000 W

Although various embodiments which incorporate the teachings of theinvention have been shown and described in detail herein, those skilledin the art can readily devise many other varied embodiments within thescope of the invention. For example, more than two chambers may be usedin tandem where the gas line is split in more than two gas deliverylines. In another embodiment, the process gas may be a mixture of gaseswhere each gas is premixed with other gases and then flowed into the GFD180. In still another embodiment, one or more fluids can be dividedthrough both gas delivery lines 139, 141 and then brought to a gaseousphase within the tandem-processing chamber 106.

While foregoing is directed to the preferred embodiment of the presentinvention, other and further embodiments of the invention may be devisedwithout departing from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. An apparatus for dividing a fluid flow from afluid source, comprising: a first fluid line connected to a fluidsource; a fluid flow meter positioned on the first fluid line to outputa signal corresponding to a first fluid flow through the first fluidline; a second fluid line connected to the fluid source; and a fluidflow controller positioned on the second fluid line for controlling asecond fluid flow therethrough; the fluid flow controller responsive tothe signal from the fluid flow meter to controllably divide a fluid flowfrom the fluid source into the first fluid flow and second fluid flow,wherein the first fluid flow is inversely responsive to the second fluidflow.
 2. The apparatus of claim 1, wherein the fluid flow controllercomprises at least one flow control input responsive to the signal fromthe fluid flow meter.
 3. The apparatus of claim 1, further comprising atandem-processing chamber connected to the first fluid line and thesecond fluid line.
 4. The apparatus of claim 1, wherein the fluid flowmeter comprises a mass flow meter.
 5. The apparatus of claim 1, whereinthe fluid flow controller comprises a mass flow controller, a gatevalve, a ball valve, a pneumatic valve, or combinations thereof.
 6. Theapparatus of claim 1, wherein the signal comprises a digital signal, anoptical signal, a mechanical signal, an electrical signal, orcombinations thereof.
 7. The apparatus of claim 1, wherein the fluidflow controller equally divides the fluid flow between the first fluidline and the second fluid line.
 8. The apparatus of claim 1, wherein thefirst fluid line, the second fluid line, and the flow control signaldefine a closed loop fluid control system responsive to the fluid flowrate through the first fluid line wherein a change in fluid flow fromthe fluid source results in a proportional change in the fluid flow ratethrough the first fluid line.
 9. The apparatus of claim 1, wherein thefluid flow meter comprises a gas orifice adapted to provide gas flowresistance.
 10. An apparatus for dividing a gas flow from a gas sourceoutput into a tandem-processing chamber, comprising: a first gas lineconnecting a gas source output to a first processing region of atandem-processing chamber; a gas flow meter positioned on the first gasline to output a signal corresponding to a first gas flow through thefirst gas line; a second gas line connecting the gas source output to asecond processing region of the tandem processing chamber; and a gasflow controller positioned on the second gas line and responsive to thesignal from the gas flow meter to divide a gas flow from the gas sourceoutput between the first gas flow through the first gas line to thefirst processing region and a second gas flow through the second gasline to the second processing region, wherein the first gas flow andsecond gas flow are inversely responsive to one another.
 11. Theapparatus of claim 10, wherein the first and second processing regionsare connected by a common vacuum source.
 12. The apparatus of claim 10,wherein the gas source output is controlled by a mass flow controller.13. The apparatus of claim 10, wherein the gas flow controller comprisesat least one flow control input responsive to the signal from the gasflow meter.
 14. The apparatus of claim 10, wherein the gas flow metercomprises a mass flow meter.
 15. The apparatus of claim 10, wherein thegas flow controller comprises a mass flow controller, a gate valve, aball valve, a pneumatic valve, or combinations thereof.
 16. Theapparatus of claim 10, wherein the signal comprises a digital signal, anoptical signal, a mechanical signal, an electrical signal, orcombinations thereof.
 17. The apparatus of claim 10, wherein the firstgas line, the second gas line, and the flow control signal define aclosed loop gas control system responsive to the gas flow rate throughthe first gas line wherein a change in gas flow from the gas flow outputresults in a proportional change in the gas flow rate through the firstgas line.
 18. A method of dividing a fluid flow from a fluid source,comprising: measuring a first fluid flow through a first fluid lineconnected to the fluid source; and controlling a second fluid flowthrough a second fluid line connected to the fluid source using thefirst fluid flow through the first fluid line, wherein the first fluidflow and second fluid flow are inversely responsive to each other,wherein the first fluid line comprises a fluid flow measuring devicethat outputs a control signal, and the second fluid line comprises afluid controller that receives the control signal.
 19. The method ofclaim 18, wherein the fluid flow is equally divided between the firstfluid line and the second fluid line.
 20. The method of claim 18,wherein the fluid flow measuring device comprises a mass flow meter. 21.The method of claim 18, wherein the control signal comprises a digitalsignal, an optical signal, a mechanical signal, an electrical signal, orcombinations thereof.
 22. A method of dividing a gas flow in atandem-processing chamber, comprising: measuring a first gas flow ratefrom a gas source through a first gas line coupled to a first processingregion of a tandem-processing chamber; and using the first gas flow rateto control a second gas flow rate from the gas source through a secondgas line coupled to a second processing region of the tandem-processingchamber, wherein changes to the first gas flow rate and the second gasflow rate are inversely proportional.
 23. The method of claim 22,wherein the gas flow is equally divided between the first gas line andthe second gas line.
 24. The method of claim 20, wherein the first gasline comprises a gas flow measuring device that outputs a controlsignal, and the second gas line comprises a gas flow controller thatreceives the control signal.
 25. The method of claim 24, wherein the gasflow measuring device comprises a mass flow meter.
 26. The method ofclaim 24, wherein the gas flow controller comprises a mass flowcontroller, a gate valve, a ball valve, a pneumatic valve, orcombinations thereof.
 27. The method of claim 25, wherein the controlsignal comprises a digital signal, an optical signal, a mechanicalsignal, an electrical signal, or combinations thereof.
 28. The method ofclaim 22, wherein the first gas line comprises a gas orifice adapted toprovide gas flow resistance.